312 LITTORINIDiE. 



Fam. LITTORINIDyE. 



Tongue long, armed with seven rows of teeth (3-1 -3), 

 the median broad and hooked, the lateral, or uncini, 

 hooked and oblong; the outer lateral teeth conical, curved. 

 Rostrum moderate, entire ; eyes sessile on the outer side 

 of the tentacles ; no neck-lobes or lateral cirrhi. Mantle 

 with a rudimentary siphonal fold in front ; gills two, one 

 very large, occupying nearly the whole surface of the 

 branchial cavity, and formed of flat, free plates. Foot 

 with a linear duplication in front, and a groove along the 

 under surface. 



Operculum horny, spiral, of few whorls. 



Shell spiral, turbinated or depressed ; aperture simple 

 in front, never pearly within. 



Genus LITTORINA, Ferussac. 



Eyes sessile near the outer bases of the tentacles. 



Operculum paucispiral. 



Shell turbinate, solid, few-whorled, axis imperforate; 

 spire short ; aperture subcircular, entire ; columellar lip 

 rather flattened ; outer lip simple, acute. 



Syn. Trocbus, Adans., not Linn. Turbo, Swains., 

 not Linn. Bacalia, Gray. 



E.V. L. littorea, Linnmis, pi. 33, fig. 1. Operculum, 

 L. littorea, fig. I, a, 1, b. Shell, L. littorea, fig. 1, c. 



The animals of this genus are, in a great measure, am- 

 phibious, living on the rocks along the shore ; many spe- 

 cies are nearly always out of the water, but usually place 

 themselves within the wash of the tide. They are very 



